Controllable synthesis of amidoximated self-propelled tubular micromotors for enhanced uranium recovery: non-invasive mixing and on-the-move capturing

Micro-/nanomotors that combine attributes of autonomous movement and adsorption performance are attractive for efficient pollutant treatment. However, micro/nanomotors design still suffers from challenges including complex manufacturing processes, specific instrument demands and low yields. Herein, we proposed amidoxime-functionalized polydopamine tubular micromotors (DNBMs-AO) and demonstrated their application for rapid selective adsorption of uranium from contaminated seawater. The whole fabrication procedure is simplified and straightforward by curcumin templating and in-situ reduction/graft method. The manganese dioxide (MnO₂) catalyst and amidoxime groups are subsequently anchored on the outer and inner side of nanotube surface. Besides, the distribution and amount of modified MnO₂ and amidoxime groups can be manipulated via directly changing the reduction time. DNBMs-AO are driven and propelled by microbubbles produced by MnO₂-triggered catalytic decomposition of hydrogen peroxide, which can reach high velocity at 302.6 μm s⁻¹. The static adsorption results indicate that the adsorption of U(VI) onto DNBMs-AO can be better described by Langmuir model with the maximum adsorption capacity of 313.9 mg/g. Moreover, the motion of DNBMs-AO can efficiently improve the U(VI) diffusion under low H₂O₂ concentration, and enhance the adsorption kinetics to approximately 2.5 times. DNBMs-AO also exhibits high selectivity towards U(VI) and excellent performance stability, endowing its potential application in environmental engineering field.